首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2473633篇
  免费   184004篇
  国内免费   5537篇
耳鼻咽喉   35048篇
儿科学   78683篇
妇产科学   71596篇
基础医学   347679篇
口腔科学   71031篇
临床医学   216131篇
内科学   487286篇
皮肤病学   57226篇
神经病学   201054篇
特种医学   96154篇
外国民族医学   879篇
外科学   376402篇
综合类   57679篇
现状与发展   8篇
一般理论   863篇
预防医学   184374篇
眼科学   57758篇
药学   180188篇
  5篇
中国医学   5444篇
肿瘤学   137686篇
  2018年   25302篇
  2017年   19642篇
  2016年   22000篇
  2015年   24739篇
  2014年   35052篇
  2013年   52780篇
  2012年   70454篇
  2011年   74584篇
  2010年   44145篇
  2009年   42525篇
  2008年   70172篇
  2007年   75193篇
  2006年   76176篇
  2005年   73915篇
  2004年   71066篇
  2003年   68283篇
  2002年   66728篇
  2001年   119213篇
  2000年   122301篇
  1999年   102660篇
  1998年   28468篇
  1997年   25840篇
  1996年   25387篇
  1995年   24075篇
  1994年   22181篇
  1993年   20705篇
  1992年   78671篇
  1991年   75602篇
  1990年   73434篇
  1989年   70874篇
  1988年   65636篇
  1987年   64245篇
  1986年   61113篇
  1985年   57987篇
  1984年   43962篇
  1983年   37196篇
  1982年   22558篇
  1981年   20338篇
  1979年   40532篇
  1978年   28790篇
  1977年   24581篇
  1976年   22554篇
  1975年   24656篇
  1974年   29293篇
  1973年   28518篇
  1972年   27048篇
  1971年   24910篇
  1970年   23756篇
  1969年   22529篇
  1968年   21261篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Setting goals to maintain hope.   总被引:3,自引:0,他引:3  
  相似文献   
72.
73.
OBJECTIVES: The aim of this study is to evaluate the effect of ZnSO(4) addition to a conventional glass ionomer and a resin-modified glass ionomer on solubility, flexural strength, zinc and fluoride (F) release, and Streptococcus mutans growth inhibition. METHODS: 5 or 10% ZnSO(4) was added to Vitremer and Ketac-Fil powders. Solubility test was performed based on ISO 7489. Flexural strength was determined by 3-point bending test based on ISO 4049. Zn release/uptake was determined by atomic emission spectrometry; F release/uptake was measured using a F-specific electrode. Both release measurements were performed for 15 d before and 15 d after recharging. Antibacterial test was conducted according to agar plate methods against S. mutans, by measuring the inhibition halos in 1-h and 15-d specimens. Data were analyzed by ANOVA. RESULTS: Solubility increased with higher ZnSO(4) content, but remained below the ISO 7489 limit. Flexural strength was not affected by ZnSO(4) addition, and Vitremer performed better than Ketac-Fil. The control materials released no zinc. Vitremer with 10% ZnSO(4) released the highest amount of zinc. Fluoride release was similar for Ketac-Fil and Vitremer. In both cases, the highest amounts were released in the first 24 h. The growth inhibition halo of S. mutans was similar for both materials with highest content of ZnSO(4) and occurred only with 1-h specimens. SIGNIFICANCE: Zinc addition decreased microorganisms growth and improved fluoride release, without significantly affecting the materials' flexural strength and solubility.  相似文献   
74.
75.
Burkitt’s lymphoma is a high-grade, rapidly growing B-cell neoplasm. It is recognized by its aggressive course, brief median survival, and low rates of long-term survival. The authors discuss the case of a patient who acutely presented with intraabdominal complications from a new onset of Burkitt’s lymphoma. The clinical and pathological features, staging, treatment options, and survival data are reviewed. In addition, the role of surgical intervention is carefully analyzed.  相似文献   
76.
We aimed to evaluate the potential of the cerebrospinal fluid (CSF) axonal damage biomarker NfH(SMI35) in the laboratory-supported differential diagnosis of parkinsonian syndromes. Patients with idiopathic Parkinson's disease (PD; n = 22), multiple-system atrophy (MSA; n = 21), progressive supranuclear palsy (PSP; n = 21), corticobasal degeneration (CBD; n = 6), and age-matched controls (n = 45) were included. CSF levels of NfH(SMI35) were measured using ELISA. Levels of CSF NfH(SMI35) were elevated in PSP compared to PD and controls (P < 0.05 each). They were also significantly higher in MSA than in PD and controls (P < 0.05 each). NfH(SMI35) differentiated PD from PSP with a sensitivity of 76.5% and a specificity of 94.4%. Axonal damage as measured by CSF NfH(SMI35) is most prominent in the more rapidly progressive syndromes PSP and MSA as compared to PD or CBD. CSF NfH(SMI35) may therefore be of some value for the laboratory-supported differential diagnosis of atypical parkinsonian syndromes.  相似文献   
77.
Levels of the soluble form of the triggering receptor expressed on myeloid cells (sTREM)-1 are elevated in severe sepsis. However, it is not known whether sTREM-1 measurements can distinguish milder bacterial infections from noninfectious inflammation. The present authors studied whether serum sTREM-1 levels differ in community-acquired pneumonia, exacerbations of chronic obstructive pulmonary disease (COPD), asthma and controls, and whether sTREM-1 may be used as a surrogate marker for the need for antibiotics. Serum sTREM-1 levels in 150 patients with pneumonia, COPD and asthma exacerbations and 62 healthy controls were measured. Serum sTREM-1 levels were significantly elevated in pneumonia (median 295.2 ng x mL(-1)), COPD (280.3 ng x mL(-1)) and asthma exacerbations (184.0 ng x mL(-1)) compared with controls (83.1 ng x mL(-1)). Levels were higher in pneumonia and Anthonisen type 1 COPD exacerbations than in type 2 and 3 COPD and asthma exacerbations. The area under the receiver operating characteristics curve for sTREM-1 as a surrogate marker for the need for antibiotics was 0.77. Serum levels of the soluble form of the triggering receptor expressed on myeloid cells-1 were elevated predominantly in pneumonia and Anthonisen type 1 COPD exacerbations versus type 2 and 3 chronic obstructive pulmonary disease exacerbations, asthma and controls. Serum levels of the soluble form of the triggering receptor expressed on myeloid cells-1 has moderate but insufficient accuracy as a surrogate marker for the need for antibiotics in lower respiratory tract infections.  相似文献   
78.
Ninety-seven inpatients with tardive dyskinesia (average AIMS score = 13), the majority of whom were schizophrenic, were studied. Forty patients were Caucasian, and 57 were African-American. The APOE genotypes of these patients were compared to previously published genotypes of controls and with previously published studies of APOE genotypes in patients with schizophrenia. There were no significant differences in APOE allele frequencies comparing the African-American tardive dyskinesia population and the African-American control groups. In contrast, significant (< 0.05) P values were obtained comparing the Caucasian tardive dyskinesia population to the Caucasian controls, when comparing allele frequencies and genotypic frequencies. This study suggests that Caucasians bearing an APOE2 allele are at increased risk of developing tardive dyskinesia, whereas African-Americans are not. APOE genotype-specific risks of both tardive dyskinesia and Alzheimer's disease that vary across populations could be due to recruitment of patients or controls or could be due to modifying effects of differing genetic or environmental backgrounds. The mechanism by which the APOE2 allele increases risk of tardive dyskinesia is not known. Further information about the mechanisms of increased risk of tardive dyskinesia could result in stratification of prescribing practices weighing the costs of medications against the relative risk of side effects.  相似文献   
79.
80.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号